TY - JOUR A1 - Thielmann, Julian A1 - Kohnen, Stephane A1 - Hauser, Carolin T1 - Antimicrobial activity of Olea europaea Linné extracts and their applicability as natural food preservative agents JF - International Journal of Food Microbiology N2 - The antimicrobial activity of phenolic compounds from Olea (O.) europaea Linné (L.) is part of the scientific discussion regarding the use of natural plant extracts as alternative food preservative agents. Although, the basic knowledge on the antimicrobial potential of certain molecules such as oleuropein, hydroxytyrosol or elenolic acid derivatives is given, there is still little information regarding their applicability for food preservation. This might be primarily due to the lack of information regarding the full antimicrobial spectrum of the compounds, their synergisms in natural or artificial combinations and their interaction with food ingredients. The present review accumulates available literature from the past 40 years, investigating the antimicrobial activity of O. europaea L. derived extracts and compounds in vitro and in food matrices, in order to evaluate their food applicability. In summary, defined extracts from olive fruit or leaves, containing the strongest antimicrobial compounds hydroxytyrosol, oleacein or oleacanthal in considerable concentrations, appear to be suitable for food preservation. Nonetheless there is still need for consequent research on the compounds activity in food matrices, their effect on the natural microbiota of certain foods and their influence on the sensorial properties of the targeted products. KW - Antimicrobial susceptibility KW - elenolic acid KW - food preservation KW - hydroxytyrosol KW - olea europaea KW - oleuropein Y1 - 2017 U6 - https://doi.org/10.1016/j.ijfoodmicro.2017.03.019 SN - 0168-1605 VL - 251 SP - 48 EP - 66 PB - Elsevier BV CY - Amsterdam ER - TY - JOUR A1 - Wiegand, Cornelia A1 - Völpel, Andrea A1 - Ewald, Andrea A1 - Remesch, Markko A1 - Kuever, Jan A1 - Bauer, Janine A1 - Griesheim, Stefanie A1 - Hauser, Carolin A1 - Thielmann, Julian A1 - Tonndorf-Martini, Silke A1 - Sigusch, Bernd W. A1 - Weisser, Jürgen A1 - Wyrwa, Ralf A1 - Elsner, Peter A1 - Hipler, Uta-Christina A1 - Roth, Martin A1 - Dewald, Carolin A1 - Lüdecke-Beyer, Claudia A1 - Bossert, Jörg T1 - Critical physiological factors influencing the outcome of antimicrobial testing according to ISO 22196 / JIS Z 2801 JF - PLOS ONE N2 - Bactericidal materials gained interest in the health care sector as they are capable of preventing material surfaces from microbial colonization and subsequent spread of infections. However, commercialization of antimicrobial materials requires proof of their efficacy, which is usually done using in vitro methods. The ISO 22196 standard (Japanese test method JIS Z 2801) is a method for measuring the antibacterial activity of daily goods. As it was found reliable for testing the biocidal activity of antimicrobially active materials and surface coatings most of the laboratories participating in this study used this protocol. Therefore, a round robin test for evaluating antimicrobially active biomaterials had to be established. To our knowledge, this is the first report on inaugurating a round robin test for the ISO 22196 / JIS Z 2801. The first round of testing showed that analyses in the different laboratories yielded different results, especially for materials with intermediate antibacterial effects distinctly different efficacies were noted. Scrutinizing the protocols used by the different participants and identifying the factors influencing the test outcomes the approach was unified. Four critical factors influencing the outcome of antibacterial testing were identified in a series of experiments: (1) incubation time, (2) bacteria starting concentration, (3) physiological state of bacteria (stationary or exponential phase of growth), and (4) nutrient concentration. To our knowledge, this is the first time these parameters have been analyzed for their effect on the outcome of testing according to ISO 22196 / JIS Z 2801. In conclusion, to enable assessment of the results obtained it is necessary to evaluate these single parameters in the test protocol carefully. Furthermore, uniform and robust definitions of the terms antibacterial efficacy / activity, bacteriostatic effects, and bactericidal action need to be agreed upon to simplify communication of results and also regulate expectations regarding antimicrobial tests, outcomes, and materials. Y1 - 2018 U6 - https://doi.org/10.1371/journal.pone.0194339 SN - 1932-6203 VL - 13 IS - 3 PB - Public Library of Science (PLoS) ER -